Heat pipe

ABSTRACT

A heat pipe comprises a housing that has a heating section that is made of metal and is contacted by a heating element, a cooling section that is made of metal and is cooled by a cooling element, and a plurality of refrigerant flow channels formed inside the housing from the heating section to the cooling section; refrigerant that is enclosed inside the plurality of refrigerant flow channels; and heat-insulating layers that are disposed between the plurality of refrigerant flow channels located at least at the heating section in the housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2011-88486 filed on Apr. 12, 2011, the disclosure ofwhich is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a heat pipe.

2. Related Art

Conventionally, flat plate-like heat pipes having plural pores inside,such as those described in Japanese Patent No. 3,438,087 and JapanesePatent Application Laid-Open (JP-A) No. 2006-52942, have been known. Inthese heat pipes, heat exchange with a heating element is performed byrefrigerant flowing through the plural pores into a heating section sideand refrigerant returning from the heating section to a cooling section.

SUMMARY

However, in the above-described heat pipes, although the refrigerantflowing into the heating section side should exchange heat only with theheating element, it also exchanges heat with the refrigerant returningthrough the adjacent pores from the heating section to the coolingsection, and so the cooling efficiency of the heating element drops.

The present invention has been made in view of the above-describedsituation and provides a heat pipe that can improve the coolingefficiency of the heating element.

A heat pipe of a first aspect of the present invention includes: ahousing that has a heating section that is made of metal and iscontacted by a heating element, a cooling section that is made of metaland is cooled by a cooling element, and plural refrigerant flow channelsformed inside the housing from the heating section to the coolingsection; refrigerant that is enclosed inside the plural refrigerant flowchannels; and heat-insulating layers that are disposed between theplural refrigerant flow channels at least in the heating section in thehousing.

According to the above heat pipe, the heat-insulating layers aredisposed between the plural refrigerant flow channels at least in theheating section in the housing. Consequently, the refrigerant flowinginto the heating section side can be suppressed from exchanging heatwith the refrigerant returning through the adjacent refrigerant flowchannels from the heating section to the cooling section. Because ofthis, the heat exchange efficiency between the refrigerant flowing intothe heating section side and the heating element can be improved, so thecooling efficiency of the heating element can be improved.

A heat pipe of a second aspect of the present invention is the heat pipeof the first aspect, wherein in the housing, groove portions are formedin partition walls between the plural refrigerant flow channels, and theheat-insulating layers are formed by a heat-insulating material fillingthe groove portions.

According to this heat pipe, by forming the groove portions in thehousing and filling the groove portions with the heat-insulatingmaterial, the heat-insulating layers can be easily formed inside thehousing.

A heat pipe of a third aspect of the present invention is the heat pipeof the first aspect, wherein in the housing, plural hole portions areformed from the heating section to the cooling section, any holeportions of the plural hole portions are made to serve as the pluralrefrigerant flow channels, and the heat-insulating layers are formed asa result of the insides of remaining hole portions of the plural holeportions being filled with a heat-insulating material.

According to this heat pipe, the housing can be easily manufacturedbecause it suffices to form the plural hole portions in the housingwithout having to distinguish between those for the refrigerant flowchannels and those for the heat-insulating layers.

A heat pipe of a fourth aspect of the present invention is the heat pipeof the first aspect, wherein the housing has a main body portion thathas a plate-like base portion and plural fins that extend in a normaldirection from the base portion and are formed in parallel to each otherand a cover portion that opposes the base portion and is fixed to distalends of the plural fins, any groove portions of groove portions betweenthe plural fins are made to serve as the plural refrigerant flowchannels, and the heat-insulating layers are formed as a result of theinsides of remaining plural groove portions of the plural grooveportions being filled with a heat-insulating material.

According to this heat pipe, the housing can be easily manufacturedbecause it suffices to form the main body portion in the form of a heatsink having the plural fins.

A heat pipe of a fifth aspect of the present invention is the heat pipeof the first aspect, wherein the housing has a heat-insulating sectionbetween the heating section and the cooling section.

According to this heat pipe, the cooling efficiency of the heatingelement can be improved more because the heating section and the coolingsection can be thermally insulated by the heat-insulating section.

A heat pipe of a sixth aspect of the present invention is the heat pipeof the fifth aspect, wherein both lengthwise direction sides of theplural refrigerant flow channels open to an end face of the housing onthe heating section side and to an end face of the housing on thecooling section side, and the heat pipe further includes a pair ofclosing portions that are disposed on the end face of the housing on theheating section side and the end face of the housing on the coolingsection side and that close openings on both lengthwise direction sidesof the plural refrigerant flow channels.

According to this heat pipe, the manufacture of the heat pipe can bemade easy because it is not necessary to swage both end portions of thehousing in order to close the openings on both lengthwise directionsides of the plural refrigerant flow channels.

A heat pipe of a seventh aspect of the present invention is the heatpipe of the sixth aspect, wherein the pair of closing portions, theheat-insulating section, and the heat-insulating layers are formedintegrally from a resin.

According to this heat pipe, costs can be reduced because the pair ofclosing portions, the heat-insulating section, and the heat-insulatinglayers are formed integrally from a resin.

As described in detail above, according to the present invention, thecooling efficiency of the heating element can be improved because theheat exchange efficiency between the refrigerant flowing into theheating section side and the heating element can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will be described in detail basedon the following figures, wherein:

FIG. 1 is a side view of a heat pipe pertaining to an embodiment of thepresent invention;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a cross-sectional view showing a first modification of theheat pipe pertaining to the embodiment of the present invention;

FIG. 5 is a cross-sectional view showing a second modification of theheat pipe pertaining to the embodiment of the present invention;

FIG. 6 is a cross-sectional view showing a third modification of theheat pipe pertaining to the embodiment of the present invention; and

FIG. 7 is a cross-sectional view showing a fourth modification of theheat pipe pertaining to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings.

As shown in FIG. 1, a heat pipe 10 pertaining to the embodiment of thepresent invention has a flat board-like housing 12. The entire housing12 is formed by metal, such as an aluminum alloy or copper, whose heatconductivity is high.

In the housing 12, one end side is made to serve as a heating section 16that is contacted by a heating element 14 that is an IGBT or MOSsemiconductor device, for example, and the other end side is made toserve as a cooling section 20 that is cooled by a cooling element 18such as a water-cooled block, a heat sink, or a gas, for example. In acase where the heating element 14 is a semiconductor device, aninsulating substrate on which an electrical circuit is disposed may alsobe placed between the heating element 14 and the heating section 16.

Inside the housing 12, as shown in FIG. 2, plural refrigerant flowchannels 22A to 22F are formed in parallel from the heating section 16to the cooling section 20. Further, at the heating section 16 side, theend portions of the refrigerant flow channel 22A and the refrigerantflow channel 22B, the end portions of the refrigerant flow channel 22Cand the refrigerant flow channel 22D, and the end portions of therefrigerant flow channel 22E and the refrigerant flow channel 22F arerespectively connected by connecting flow channels 24A to 24C thatextend in the direction in which the plural refrigerant flow channels22A to 22F are lined up.

At the cooling section 20 side, the end portions of the refrigerant flowchannel 22B and the refrigerant flow channel 22C and the end portions ofthe refrigerant flow channel 22D and the refrigerant flow channel 22Eare likewise respectively interconnected by connecting flow channels 24Dand 24E that extend in the direction in which the plural refrigerantflow channels 22A to 22F are lined up. An open circuit-like inside flowchannel 26 is thus formed inside the housing 12 as a result of theplural refrigerant flow channels 22A to 22F being connected by theplural connecting flow channels 24A to 24E in this manner.

Within the inside flow channel 26, an organic liquid such as water,Freon, or butane is enclosed as refrigerant 28. In the heat pipe 10, theheat of the heating element 14 moves via the refrigerant 28 from theheating section 16 to the cooling section 20. That is, the heat pipe 10is configured as a self-excited heat pipe.

Further, as shown in FIG. 2 and FIG. 3, in the housing 12, grooveportions 32 are formed in partition walls 30A to 30E provided in theplural refrigerant flow channels 22A to 22F. The groove portions 32 areformed from the heating section 16 through the cooling section 20.

Additionally, the groove portions 32 are filled with a heat-insulatingmaterial, whereby heat-insulating layers 34 are formed in the pluralrefrigerant flow channels 22A to 22F. As the heat-insulating materialforming the heat-insulating layers 34, a gas such as air, or a resin,ceramic, or metal respective thermal conductivities are low, or amaterial obtained by making these materials into a porous body byfoaming or the like, is used. Further, the heat-insulating layers 34 mayalso be vacuum layers.

The heat pipe 10 is manufactured in the following way, for example. Thatis, first, a porous flat tube having plural hole portions that becomethe basis of the plural refrigerant flow channels 22A to 22F is createdby extrusion. Then, the groove portions 32 are formed in the partitionwalls 30A to 30E by cutting or the like, for example. Next, the grooveportions 32 are filled with the heat-insulating material that becomesthe basis of the heat-insulating layers 34, and thereafter these areheated and fired.

Then, the end portions of the partition walls 30A, 30C, and 30E on theheating section 16 side are cut to form interstices that become thebasis of the connecting flow channels 24A to 24C, and the end portionsof the partition walls 30B and 30D on the cooling section 20 side arecut to form interstices that become the basis of the connecting flowchannels 24D and 24E.

Next, one of the end portions of the housing 12 on the heating section16 side and the cooling section 20 side is swaged by spot welding, andthe refrigerant 28 is put into the plural refrigerant flow channels 22Ato 22F. Then, the other of the end portions of the housing 12 on theheating section 16 side and the cooling section 20 side is swaged byspot welding to form the open circuit-like inside flow channel 26 withinthe housing 12. The heat pipe 10 is manufactured in the above way.

Next, the action and effects of the embodiment of the present inventionwill be described.

According to this heat pipe 10, the heat-insulating layers 34 aredisposed between the plural refrigerant flow channels 22A to 22F.Consequently, the refrigerant 28 flowing into the heating section 16from the cooling section 20 can be suppressed from exchanging heat withthe refrigerant returning through the adjacent refrigerant flow channelsfrom the heating section 16 to the cooling section 20. Because of this,the heat exchange efficiency between the refrigerant flowing into theheating section 16 and the heating element 14 can be improved, so thecooling efficiency of the heating element 14 can be improved.

Further, by forming the plural groove portions 32 by additional work inthe housing 12 and filling the groove portions 32 with theheat-insulating material, the plural heat-insulating layers 34 can beeasily formed inside the housing 12.

Next, modifications of the embodiment of the present invention will bedescribed.

In the above-described embodiment, the heat-insulating layers 34 areformed from the heating section 16 to the cooling section 20, but, forexample, as shown in FIG. 4, the heat-insulating layers 14 may also beformed just in the heating section 16.

Further, for example, as shown in FIG. 4, in a case where narrowpartition walls 30A, 30C, and 30E and wide partition walls 30B and 30Dare alternately formed between the plural refrigerant flow channels 22Ato 22F, the heat-insulating layers 34 may also be disposed just in thenarrow partition walls 30A, 30C, and 30E.

Further, in the above-described embodiment, the inside flow channel 26is provided in the form of an open circuit, but, for example, as shownin FIG. 4, the inside flow channel 26 may also be provided in the formof a closed circuit as a result of a connecting flow channel 24F thatconnects the end portions of the refrigerant flow channel 22A and therefrigerant flow channel 22F being formed only on the cooling section 20side.

Further, as shown in FIG. 5, in the housing 12, plural hole portions 36may also be formed from the heating section 16 to the cooling section 20(see FIG. 1 for both), in such a manner that hole portions 36 providedon both sides and lined up every other one from these hole portions 36are made to serve as the plural refrigerant flow channels 22A to 22F.Additionally, the heat-insulating layers 34 may also be formed betweenthe plural refrigerant flow channels 22A to 22F as a result of remainingplural hole portions 36 being filled with a heat-insulating materialsuch as a polyamide resin, for example.

According to this modification, the housing 12 can be manufactured moreeasily by extrusion molding or the like because it suffices to form theplural hole portions 36 in the housing 12 without having to distinguishbetween those for the refrigerant flow channels and those for theheat-insulating layers.

Further, the housing 12 may also be configured as shown in FIG. 6. Thatis, in the modification shown in FIG. 6, the housing 12 is divided intoa main body portion 38 and a cover portion 40.

The main body portion 38 has a plate-like base portion 41 and pluralfins 44 that extend in a normal direction from the base portion 41 andare formed in parallel to each other. The plural fins 44 are formed fromthe heating section 16 to the cooling section 20 (see FIG. 1 for both).The cover portion 40 is formed in a plate-like shape similar to the baseportion 41, opposes the base portion 41, and is fixed to distal ends ofthe plural fins 44. Further, wall portions 45 that extend toward thebase portion 41 side are formed on both sides of the cover portion 40.

Additionally, any plural groove portions 42A to 42F of groove portionsbetween the plural fins 44 are made to serve as the refrigerant flowchannels 22A to 22F. Further, the heat-insulating layers 34 are formedas a result of the insides of remaining plural groove portions 46A to46E of the groove portions between the plural fins 44 being filled witha heat-insulating material.

According to this modification, the housing 12 can be easilymanufactured because it suffices to form the main body portion 38 in theform of a heat sink having the plural fins 44.

The positions of the first groove portions 42A to 42F and the secondgroove portions 46A to 46E may also be opposite.

Further, the housing 12 may also be configured such as shown in FIG. 7.That is, in the modification shown in FIG. 7, the housing 12 isconfigured to have, in addition to the heating section 16 and thecooling section 20 that are formed in blocks, a heat-insulating section48 that is likewise formed in a block. The heating section 16 and thecooling section 20 are made of metal, and the heat-insulating section 48is made from a resin. Further, the heat-insulating section 48 is placedbetween the heating section 16 and the cooling section 20.

Inside the housing 12 that is configured to have the heating section 16,the cooling section 20, and the heat-insulating section 48, the pluralrefrigerant flow channels 22A to 22C are formed from the heating section16 through the heat-insulating section 48 to the cooling section 20.Both lengthwise direction sides of the plural refrigerant flow channels22A to 22C open to an end face 16A of the heating section 16 and to anend face 20A of the cooling section 20. The end face 16A locates at theopposite side of the heat-insulating section 48 side (an end face of thehousing 12 on the heating section 16 side) and the end face 20A locatesat the opposite side of the heat-insulating section 48 side (an end faceof the housing 12 on the cooling section 20 side).

Further, in the heating section 16, hole portions 52 are formed inpartition walls 50 between the plural refrigerant flow channels 22A to22C. Both lengthwise direction sides of the hole portions 52 open to theend face 16A of the heating section 16 and to an end face 16B of theheating section 16 at the heat-insulating section 48 side.Heat-insulating layers 54 are formed as a result of the insides of thehole portions 52 being filled with a heat-insulating material.

In the cooling section 20, hole portions 58 are formed in partitionwalls 56 between the plural refrigerant flow channels 22A to 22C. Bothlengthwise direction sides of the hole portions 58 open to the end face20A of the cooling section 20 and to an end face 20B of the coolingsection 20 at the heat-insulating section 48 side. Heat-insulatinglayers 60 are formed as a result of the insides of the hole portions 58being filled with a heat-insulating material.

Moreover, in this modification, a pair of closing portions 62 made froma resin are added. The pair of closing portions 62 are disposed on theend face 16A of the heating section 16 and on the end face 20A of thecooling section 20 and close openings on both lengthwise direction sidesof the plural refrigerant flow channels 22A to 22C as well as openingson one lengthwise direction side of each of the plural hole portions 52and 58.

According to this modification, the cooling efficiency of the heatingelement 14 can be improved more because the heating section 16 and thecooling section 20 can be thermally insulated by the heat-insulatingsection 48.

Further, the manufacture of the heat pipe 10 can be made easy because itis not necessary to swage both end portions of the housing 12 in orderto close the openings on both lengthwise direction sides of the pluralrefrigerant flow channels 22A to 22C.

The heat-insulating section 48, the heat-insulating layers 54 and 60,and the pair of closing portions 62 may also be formed integrally by aresin. Doing so can reduce costs.

Of the plural modified embodiments described above, the embodiments thatcan be combined may of course be appropriately selected and implemented.

An embodiment of the present invention has been described above, but thepresent invention is not limited to the above description and, inaddition to the above description, can of course also be variouslymodified and implemented in a range not departing from the gist thereof.

1. A heat pipe comprising: a housing that has a heating section that ismade of metal and is contacted by a heating element, a cooling sectionthat is made of metal and is cooled by a cooling element, and aplurality of refrigerant flow channels formed inside the housing fromthe heating section to the cooling section; refrigerant that is enclosedinside the plurality of refrigerant flow channels; and heat-insulatinglayers that are disposed between the plurality refrigerant flow channelslocated at least at the heating section in the housing.
 2. The heat pipeaccording to claim I, wherein in the housing, groove portions are formedin partition walls between the plurality of refrigerant flow channels,and the heat-insulating layers are formed by a heat-insulating materialfilling the groove portions.
 3. The heat pipe according to claim 1,wherein in the housing, a plurality of hole portions are formed from theheating section to the cooling section, any hole portions of theplurality of hole portions are made to serve as the plurality ofrefrigerant flow channels, and the heat-insulating layers are formed asa result of the insides of remaining hole portions of the plurality ofhole portions being filled with a heat-insulating material.
 4. The heatpipe according to claim 1, wherein the housing has a main body portionthat has a plate-like base portion and a plurality of fins that extendin a normal direction from the base portion and are formed in parallelto each other and a cover portion that opposes the base portion and isfixed to distal ends of the plurality of fins, any groove portions ofgroove portions between the plurality of fins are made to serve as theplurality of refrigerant flow channels, and the heat-insulating layersare formed as a result of the insides of remaining groove portions ofthe groove portions between the plurality of fins being filled with aheat-insulating material.
 5. The heat pipe according to claim 1, whereinthe housing further has a heat-insulating section between the heatingsection and the cooling section.
 6. The heat pipe according to claim 5,wherein both lengthwise direction sides of the plurality of refrigerantflow channels open to an end face of the housing on the heating sectionside and to an end face of the housing on the cooling section side, andthe heat pipe further comprises a pair of closing portions that aredisposed on the end face of the housing on the heating section side andthe end face of the housing on the cooling section side and that closeopenings on both lengthwise direction sides of the plurality ofrefrigerant flow channels.
 7. The heat pipe according to claim 6,wherein the pair of closing portions, the heat-insulating section, andthe heat-insulating layers are formed integrally from a resin.